1. Field of the Invention
This invention relates to the pulverization of solids, and more particularly to the pulverization of solids in a fluid medium.
2. Brief Description of the Prior Art
The disposal of drill cuttings has been a longstanding problem in the field of well drilling and this problem has recently received attention due to increased concern regarding the environment. Offshore drilling operations, in particular, are problematic because the transport of the cuttings to a landfill or a shore-based processing system is required. One solution to this problem is disclosed in U.S. Pat. Nos. 5,109,933 and 5,129,469. The prior art system for disposing of drill cuttings as described in these patents involves mixing the cuttings with a carrier liquid, such as water, and reducing the size of the cuttings in a pump having an impeller of a backward swept blade type to form a slurry of the particles and the carrier liquid for injection into a well for disposal.
Particle size reduction is also used in mining processes, preparation of limestone, etc. Pulverizers and material breaking machinery are described, for example, in the following U.S. Pats.: No. 310,940 to Gould; No. 315,064 to Pratt; No. 345,408 to Birge; No. 359,630 to Pratt; No. 666,404 to Wurster; No. 2,049,920 to McNitt; No. 3,927,840 to Nash; No. 3,931,936 to Petry et al.; and No. 4,947,906 to Schroeder.
In copending application Ser. No. 08/170,056, herein incorporated by references, there is described an apparatus for pulverizing drill cuttings from a well bore comprised of a pair of interconnected cylindrical chambers wherein each chamber is provided with a rotatable shaft having a plurality of disc sets mounted thereon wherein the shafts are aligned in parallel relation and operate in a counter rotating manner and wherein each disc set includes at least one pivotally mounted thrust guide in the form of a bar-shaped member. With particulate solids of a size greater than about 50 mesh, power requirements were excessive on initial pulverizing stages. Additionally, there is excessive fluid leakage about the shafts extending through the chambers.